Introduction to the Haiyan Triangle City ruins: The Haiyan Triangle City ruins are located on the golden and silver beach with abundant water and grass in the northeast of Qinghai Lake in Haiyan County, Haibei Tibetan Autonomous Prefecture, Qinghai Province. It is 90 kilometers away from Xining City. It is locally known as " "Triangle City" is the site of Xihai County in the Han Dynasty. The triangular city is 650 meters long from east to west and 600 meters wide from north to south. The remaining height of the city wall is 4 meters, and the four gates can still be vaguely visible. Stone tigers and Han Dynasty coins engraved with "Xihai County was founded in Henan" have been unearthed.